Neat idea to make our own HA water. Go to http://alkalinewatermachinereviews.com and search for make your own alkaline water.
Simple water recipe and you are right about the baking soda. The recipe also includes sea salt, coral calcium powder and lemon juice. Also buy ph test strips. Both coral calcium powder and ph test strips sold at Walmart, Walgreens and Amazon. I was surprised by the addition of lemon juice, as Iemon is acidic, but they state that once digested the lemon juice affect is alkaline and it adds a pleasant taste. All ingredients in 1 gallon of water are 1 teaspoon except lemon juice, which is juice of 1 lemon. I will try but add perhaps just a teaspoon of lemon.